This invention relates to a method and apparatus for controlling the yaw response of a vehicle as it negotiates a turn. More specifically, it relates to a yaw management system that uses driveline torque control to manage the handling capabilities of the vehicle.
A vehicle is subjected to many different degrees of free movement. In most analyses, these degrees of movement are characterized as movements about three perpendicular axes, namely, rolling movement about an axis extending from front to rear through the vehicle, pitching movement about an axis extending from left to right through the vehicle, and yawing movement about an axis extending from top to bottom through the vehicle. The yawing movement of a vehicle is usually encountered when the vehicle is negotiating a turn or as vehicle looses control from loss of traction as it enters into an uncontrolled spin. The yaw is described as the angle of change from initial orientation to subsequent orientation and can be measured in terms of degrees. The yaw rate is the angular change over time, usually measured in terms of degrees per unit time. Vehicle yaw rate increases as a vehicle enters a curve or spin and then decreases as the vehicle alignment is straightened.
Recently, traction control devices have been created to adjust the yaw response of a vehicle by limiting the rotational velocity at the wheels of the vehicle. Traction control is a known system in which a device is used to control the traction of a vehicle under different road conditions. Traction control is accomplished, for example, by providing a braking system that restricts the rotational speed of any particular wheel of the vehicle. A typical braking traction control system works like an antilock braking system (ABS) in reverse. ABS is a known braking system that electronically monitors vehicle wheel speed and accordingly regulates hydraulic pressure to the brakes to maximize braking power and prevent the wheels from locking. Braking traction control systems use ABS components, except that the brakes are applied to prevent a wheel from spinning rather than preventing a wheel from locking.
Although braking traction control systems have some value, it would be desirable to develop an improved yaw management system.
According to this invention there is provided a yaw management system for a vehicle including two drive wheels, each connected to a differential by a right half axle and a left half axle, and a prop shaft to supply rotative force to the differential. Also provided is a yaw sensor for sensing the rate of change of yaw of the vehicle, and a torque transfer apparatus for selectively transferring the torque from the differential to the right half axle and left half axle. A controller is provided to receive information from the yaw sensor and to control the torque transfer apparatus in response to the information from the yaw sensor.
According to this invention there is also provided a yaw management system for a vehicle including two drive wheels, each connected to a differential by a right half axle and a left half axle, and a prop shaft to supply rotative force to the differential. Also provided is a yaw sensor for sensing the rate of change of yaw of the vehicle, and a steering wheel angle sensor for sensing the steering angle. A torque transfer apparatus for selectively transferring the torque from the differential to the right half axle and left half axle is also provided. A controller is provided to receive information from the yaw sensor and the steering wheel angle sensor to control the torque transfer apparatus in response to the information from the sensors.
According to this invention there is also provided a yaw management system for a vehicle including two drive wheels, each connected to a differential by a right half axle and a left half axle, and a prop shaft to supply rotative force to the differential. Also provided is a yaw sensor for sensing the rate of change of yaw of the vehicle, and a speed sensor for sensing the speed of the vehicle. A torque transfer apparatus for selectively transferring the torque from the differential to the right half axle and left half axle is also provided. A controller is provided to receive information from the yaw sensor and the steering speed sensor to control the torque transfer apparatus in response to the information from the sensors.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.